JP4211074B2

JP4211074B2 - Magnetic signal detector

Info

Publication number: JP4211074B2
Application number: JP00562398A
Authority: JP
Inventors: 幸雄堺; 志津枝田中
Original assignee: Panasonic Corp; Matsushita Electric Industrial Co Ltd
Current assignee: Panasonic Corp; Panasonic Holdings Corp
Priority date: 1998-01-14
Filing date: 1998-01-14
Publication date: 2009-01-21
Anticipated expiration: 2018-01-14
Also published as: JPH11202037A

Description

【０００１】
【発明の属する技術分野】
本発明は、携帯電話やコードレス電話やページャなどの移動体通信機器に利用される磁気信号検出装置に関する。
【０００２】
【従来の技術】
従来、この種の磁気信号検出装置は図８に示す構成となっていた。図８において、１１は第１の磁気抵抗、１２は第２の磁気抵抗、１３は第３の磁気抵抗、１４は第４の磁気抵抗、１５は第１の出力端子、１６は第２の出力端子、１７は電源端子、１８は接地端子、２０は演算増幅器、２６は信号出力端子であり、磁界の強さによって変化する第１の磁気抵抗１１、第２の磁気抵抗１２、第３の磁気抵抗１３、第４の磁気抵抗１４へ電源端子１７から流れる電流の変化により、第１の出力端子１５と第２の出力端子１６の直流電圧を直接的に演算増幅器２０に入力し、磁気信号の検出を行っていた。
【０００３】
【発明が解決しようとする課題】
しかしながら上述した従来技術の構成では、演算増幅器へ外乱ノイズが入力した場合、あるいは演算増幅器の入力オフセット電圧が温度変動した場合、あるいは電源電圧を間欠動作させた場合、磁気信号検出装置が誤動作するという課題があった。この磁気信号検出装置においては、耐ノイズ特性の向上、演算増幅器の入力オフセット電圧依存性の削減、電源電圧の間欠動作時における安定動作が要求されている。
【０００４】
本発明は、第１の演算増幅器と第２の演算増幅器で構成した差動型演算増幅回路の入力端子を、コンデンサを介して接地することにより、磁気信号検出装置のコモンモードノイズをキャンセルして耐ノイズ特性を向上させるとともに、高周波的に低インピーダンス化して演算増幅器の入力オフセット電圧の変動による誤動作を防止させ、電源電圧の間欠動作時に安定動作を実現させることを目的とする。
【０００５】
【課題を解決するための手段】
この課題を解決するために本発明による磁気信号検出装置は、抵抗ブリッジ回路を構成する第１の磁気抵抗と第２の磁気抵抗の接続点を第１の出力端子とするとともに第３の磁気抵抗と第４の磁気抵抗の接続点を第２の出力端子とし、前記第１の磁気抵抗と前記第４の磁気抵抗の接続点を電源端子とし、前記第２の磁気抵抗と前記第３の磁気抵抗の接続点を接地し、前記第１の出力端子を第１の演算増幅器に接続し、前記第２の出力端子を第２の演算増幅器に接続し、前記第１の演算増幅器の出力端子と前記第２の演算増幅器の出力端子とを前記第３の演算増幅器に接続し、電源端子を間欠動作させるとともに、前記第１および第３の磁気抵抗は、前記第２および第４の磁気抵抗より小さい抵抗値を有し、前記第１の演算増幅器の入力端子を第１のコンデンサを介して接地することを特徴とするものである。
【０００６】
これにより磁気信号検出装置のコモンモードノイズをキャンセルして耐ノイズ特性が向上するとともに、演算増幅器の入力オフセット電圧変動による誤動作が防止でき、さらに高周波的に低インピーダンス化して電源電圧の間欠動作時に安定動作が可能となる。
【０００７】
【発明の実施の形態】
本発明の請求項１に記載の発明は、抵抗ブリッジ回路を構成する第１の磁気抵抗と第２の磁気抵抗の接続点を第１の出力端子とするとともに第３の磁気抵抗と第４の磁気抵抗の接続点を第２の出力端子とし、前記第１の磁気抵抗と前記第４の磁気抵抗の接続点を電源端子とし、前記第２の磁気抵抗と前記第３の磁気抵抗の接続点を接地し、前記第１の出力端子を第１の演算増幅器に接続し、前記第２の出力端子を第２の演算増幅器に接続し、前記第１の演算増幅器の出力端子と前記第２の演算増幅器の出力端子とを前記第３の演算増幅器に接続し、電源端子を間欠動作させるとともに、前記第１および第３の磁気抵抗は、前記第２および第４の磁気抵抗より小さい抵抗値を有し、前記第１の演算増幅器の入力端子を第１のコンデンサを介して接地したものであり、コモンモードノイズがキャンセルされ、磁気信号検出装置の耐ノイズ特性を向上させるとともに、演算増幅器の入力オフセット電圧の変動による誤動作を防止し、高周波的に低インピーダンス化され、電源電圧の間欠動作時に誤動作のない安定動作が実現できるという作用を有する。
【０００８】
請求項２記載の発明は、第１の磁気抵抗と第３の磁気抵抗を同方向に配置し、第２の磁気抵抗と第４の磁気抵抗を同方向に配置し、前記第１の磁気抵抗と前記第３の磁気抵抗の配置方向と前記第２の磁気抵抗と前記第４の磁気抵抗の配置方向が直角になるように構成した請求項１記載の磁気信号検出装置としたものであり、一定磁界に対し第１の出力端子と第２の出力端子の間の出力電圧を最大にするという作用を有する。
【０００９】
請求項３記載の発明は、第１の磁気抵抗と第３の磁気抵抗は、同一の抵抗値を有し、第２の磁気抵抗と第４の磁気抵抗は、同一の抵抗値を有するように構成した請求項１記載の磁気信号検出装置としたものであり、無磁界時に磁気信号検出装置がチャタリングするのを防止するという作用を有する。
【００１０】
本発明は、第１の演算増幅器の反転入力端子と第１の演算増幅器の出力端子の間に第１の固定抵抗を接続し、第２の演算増幅器の反転入力端子と第２の演算増幅器の出力端子の間に第２の固定抵抗を接続し、第１の演算増幅器の反転入力端子と第２の演算増幅器の反転入力端子の間に第３の固定抵抗を接続し、第１の固定抵抗と第２の固定抵抗は、同一の抵抗値を有し、第３の固定抵抗は、前記第１の固定抵抗と前記第２の固定抵抗より小さい抵抗値を有するように構成することにより、第１の演算増幅器と第２の演算増幅器で構成した差動型演算増幅回路の正利得により、磁気信号検出装置の耐ノイズ特性を向上させるという作用を有する。
【００１１】
本発明は、第１の演算増幅器の反転入力端子と第１の演算増幅器の出力端子の間に第１の固定抵抗を接続し、第２の演算増幅器の反転入力端子と第２の演算増幅器の出力端子の間に第２の固定抵抗を接続し、第１の演算増幅器の反転入力端子と第２の演算増幅器の反転入力端子の間に第３の固定抵抗を接続し、第１の磁気抵抗と第２の磁気抵抗と第３の磁気抵抗と第４の磁気抵抗で構成した抵抗ブリッジを磁気抵抗素子とし、第１の演算増幅器と第２の演算増幅器と第３の演算増幅器と第１の固定抵抗と第２の固定抵抗と第３の固定抵抗で構成した回路ブロックを半導体集積装置とすることにより、磁気信号検出部分を単独で任意の場所に実装できるという作用を有する。
【００１２】
本発明は、磁気抵抗素子と前記半導体集積装置との接続を多層基板の内層配線で接続することにより、出力電圧に外乱ノイズが重畳するのを防ぐという作用を有する。
【００１３】
本発明は、前述の第１の演算増幅器と第２の演算増幅器と第３の演算増幅器と第１の固定抵抗と第２の固定抵抗と第３の固定抵抗で構成した半導体集積装置において、前記第１の演算増幅器の反転入力端子と前記第２の演算増幅器の反転入力端子との間に接地端子を設けることにより、第１の演算増幅器の非反転入力端子と第２の演算増幅器の非反転入力端子の分離特性を向上させ磁気信号検出装置の誤動作を防ぐという作用を有する。
【００１４】
本発明は、磁気抵抗素子の電源端子と半導体集積装置の電源は共通の電源経路から供給するように構成することにより、間欠動作時でも、同一のレギュレータから電源を供給できるという作用を有する。
【００１５】
以下、本発明の実施の形態について、図１から図７を用いて説明する。
【００１６】
（実施の形態１）
図１は、本発明の第１の実施の形態による磁気信号検出装置を示す電気回路図である。第１の磁気抵抗１１と第２の磁気抵抗１２と第３の磁気抵抗１３と第４の磁気抵抗１４は、抵抗ブリッジ回路構成の磁気抵抗素子１９としており、第１の磁気抵抗１１と第４の磁気抵抗１４の接続点は電源端子１７とし、第２の磁気抵抗１２と第３の磁気抵抗１３の接続点は接地端子１８としている。また、第１の磁気抵抗１１と第２の磁気抵抗１２の接続点を第１の出力端子１５とし、第３の磁気抵抗１３と第４の磁気抵抗１４を第２の出力端子１６としている。
【００１７】
電源端子１７より与えられる直流電圧により、磁気抵抗素子１９に電流が流れ、第１の出力端子１５には第１の磁気抵抗１１に流れる電流の電圧降下分の直流電圧が発生し、第２の出力端子１６には第４の磁気抵抗１４に流れる電流の電圧降下分の直流電圧が発生する。なお、磁気抵抗素子１９の電源端子１７と接地端子１８および第１の出力端子１５と第２の出力端子１６は、互いに対向するような配置であればよい。
【００１８】
そして、この状態において、第１の出力端子１５が第１の演算増幅器２１の非反転入力端子に接続されており、第２の出力端子１６が第２の演算増幅器２２の非反転入力端子に接続されている。このように第１の出力端子１５からの直流電圧信号を第１の演算増幅器２１で比較し、第２の出力端子１６からの直流電圧信号を第２の演算増幅器２２で比較することにより、差動型で回路を動作させることが可能となり、周囲の温度環境の変動により第１の演算増幅器２１と第２の演算増幅器２２の内部オフセット電圧が変化しても第１の出力端子１５からの直流電圧信号と第２の出力端子１６からの直流電圧信号が相対的に変化しないようにしている。
【００１９】
更に、第１の出力端子１５が第１の演算増幅器２１の非反転入力端子と第２の演算増幅器２２の非反転入力端子にコモンモードノイズが入力しても、第１の演算増幅器２１の出力端子及び第２の演算増幅器２２の出力端子の間で互いにコモンモードノイズがキャンセルされ、結果として耐ノイズ特性の向上が図られる。
【００２０】
第１の固定抵抗２３は、第１の演算増幅器２１の非反転入力端子と第１の演算増幅器２１の出力端子の間に接続しており、第１の演算増幅器２１を非反転直流増幅させている。また、第２の固定抵抗２４は、第２の演算増幅器２２の非反転入力端子と第２の演算増幅器２２の出力端子の間に接続しており、第２の演算増幅器２２を非反転直流増幅させている。また、第３の固定抵抗２５は、第１の演算増幅器２１の反転入力端子と第２の演算増幅器２２の反転入力端子の間に接続しており、第１の演算増幅器２１の反転入力端子と第２の演算増幅器２２の反転入力端子の間の直流電位を共通にするために設けている。第３の演算増幅器２０は、第１の演算増幅器２１の直流電圧出力と第２の演算増幅器２２の直流電圧出力を比較するために設けており第１の磁気抵抗１１と第２の磁気抵抗１２と第３の磁気抵抗１３と第４の磁気抵抗１４で検出した磁気信号を最終的に判別するコンパレータとして動作させている。
【００２１】
なお、ここで、第１のコンデンサ２７を第１の演算増幅器２１の非反転入力端子と接地間に接続している。このように、第１の演算増幅器２１の非反転入力端子の入力インピーダンスを第１のコンデンサ２７で決定される周波数に対して高周波的に低インピーダンス化することにより、磁気信号検出の誤動作を防止し、電源端子１７を間欠動作（パルス的動作）させても、安定に動作させることが可能となる。
【００２２】
なお、第１のコンデンサ２７は、第１の演算増幅器２１の非反転入力端子付近と接地間に接続することが望ましく、場合によっては、第２の演算増幅器２２の非反転入力端子付近と接地間に接続しても構わない。また、第１のコンデンサ２７を第１の演算増幅器２１の非反転入力端子付近と接地間および第２の演算増幅器２２の非反転入力端子付近と接地間の両方に接続してもよいことを加えておく。更に、第１の演算増幅器２１と第２の演算増幅器２２と第３の演算増幅器２０の電源を電源端子１７と同じタイミングで間欠動作させても問題ないことを加えておく。
【００２３】
次に、具体的な動作について、説明を加えておく。携帯電話を保持するカーアダプタ側には、磁石が設けられており、携帯電話側には、磁気抵抗素子１９が設けられる。携帯電話をカーアダプタに装着するかもしくは近づけると、カーアダプタ側に設けられた磁石により携帯電話側の磁気抵抗素子１９が反応し、第１の出力端子１５と第２の出力端子１６の直流電位が反転する。この信号は、第１の演算増幅器２１と第２の演算増幅器２２で直流増幅され、最終的に第３の演算増幅器２０で判別される。この判別された信号により携帯電話のフック動作を自動的に動作させている。すなわち、携帯電話をカーアダプタに装着するかもしくは近づけた時には、オフフックとなるように制御する。逆に携帯電話をカーアダプタから着脱するかもしくは遠ざけるとオンフックするように制御すれば、自動フック動作が可能となる。
【００２４】
（実施の形態２）
図２は、本発明の第２の実施の形態を示す磁気信号検出装置の上面配置図である。図２に示すように、第１の磁気抵抗１１と第３の磁気抵抗１３は、水平方向に配置し、第２の磁気抵抗１２と第４の磁気抵抗１４を垂直方向に配置している。そしてこの状態において、第１の磁気抵抗１１と第２の磁気抵抗１２と第３の磁気抵抗１３と第４の磁気抵抗１４が互いに隣りあう磁気抵抗に対し、９０度傾いた方向となるように配置させている。
【００２５】
このように配置させることにより、電源端子１７と接地端子１８の方向の磁界に対しては、対角位置にある第２の磁気抵抗１２と第４の磁気抵抗１４だけが反応するようになり、結果として第２の磁気抵抗１２と第４の磁気抵抗１４の抵抗値が変化し、第１の出力端子１５と第２の出力端子１６の直流電位が変化して、磁気信号を検出することが可能となる。
【００２６】
このとき、第１の磁気抵抗１１と第２の磁気抵抗１２と第３の磁気抵抗１３と第４の磁気抵抗１４の抵抗材料は同一成分のもので構成するようにしており、抵抗材料の温度係数を揃えることで磁気信号検出装置の温度特性を向上させている。
【００２７】
なお、必ずしも第１の磁気抵抗１１と第２の磁気抵抗１２と第３の磁気抵抗１３と第４の磁気抵抗１４の４つの磁気抵抗が、同一材料から構成されなければならないとは限らないことを加えておく。
【００２８】
また、第１の磁気抵抗１１と第３の磁気抵抗１３は同じ抵抗値としており、第２の磁気抵抗１２と第４の磁気抵抗１４は同じ抵抗値とするとともに第１の磁気抵抗１１と第３の磁気抵抗１３の抵抗値より大きい抵抗値となるようにしている（つまり第１、第３の磁気抵抗１１、１３は第２、第４の磁気抵抗１２、１４の抵抗値よりも小さくなっている。）。このような関係に構成することにより磁気信号が無い状態における磁気信号検出装置のチャタリング防止を実現しており、磁気信号検出装置の安定動作が可能となる。
【００２９】
なお、第１の磁気抵抗１１と第３の磁気抵抗１３は、第２の磁気抵抗１２と第４の磁気抵抗１４と比較して、大きい抵抗値としても構わない。
【００３０】
また、第１の固定抵抗２３と第２の固定抵抗２４は同じ抵抗値としており、第３の固定抵抗２５は、第１の固定抵抗２３と第２の固定抵抗２４より小さい抵抗値としている。この時、第３の固定抵抗２５の抵抗値は、少なくとも、第１の固定抵抗２３と第２の固定抵抗２４の抵抗値と比較して、１／５より大きい抵抗値となるように設定しており、第１の演算増幅器２１及び第２の演算増幅器２２の出力が低下しないように配慮している。
【００３１】
（実施の形態３）
図３は本発明の第３の実施の形態を示す磁気信号検出装置の上面配置図である。なお、第２の実施の形態と同一の構成の部分については、同一番号を付して詳細な説明を省略する。図に示すごとく、第１の磁気抵抗１１と第２の磁気抵抗１２と第３の磁気抵抗１３と第４の磁気抵抗１４による抵抗ブリッジ回路を磁気抵抗素子１９として構成している。このように、構成することにより、磁気抵抗を検出する部分だけを独立させることができ、任意の場所に、この磁気抵抗素子１９を配置させることが可能となる。
【００３２】
また、第１の磁気抵抗１１と第４の磁気抵抗１４の接続点である電源端子１７および第２の磁気抵抗１２と第３の磁気抵抗１３の接続点である接地端子１８および第１の磁気抵抗１１と第２の磁気抵抗１２の接続点である第１の出力端子１５および第３の磁気抵抗１３と第４の磁気抵抗１４の接続点である第２の出力端子１６は、いずれも磁気抵抗素子１９の４つの角に、それぞれの端子を設けており、互いの端子間距離が最大となるように構成している。この配置により、端子間の分離特性が向上でき、隣接する端子間での干渉を低減させている。
【００３３】
（実施の形態４）
図４は本発明の第４の実施の形態を示す磁気信号検出装置の電気回路図である。なお、第１の実施の形態と同一の構成の部分については、同一番号を付して詳細な説明を省略する。図４に示すごとく、磁気抵抗素子１９は、第１の磁気抵抗１１と第２の磁気抵抗１２と第３の磁気抵抗１３と第４の磁気抵抗１４による抵抗ブリッジ回路で構成しており、半導体集積装置２９は、第１の演算増幅器２１と第２の演算増幅器２２と第３の演算増幅器２０と第１の固定抵抗２３と第２の固定抵抗２４と第３の固定抵抗２５で構成している。
【００３４】
このように、磁気信号を検出する部分と出力信号を処理する部分とに分割することにより、磁気信号検出部を任意の位置に構成することができ、部品の実装自由度が向上するとともに、装置全体の実装効率改善が図られる。
【００３５】
なお、第１の演算増幅器２１と第２の演算増幅器２２は、同一のプロセスで製造した半導体集積装置が望ましいが、第３の演算増幅器２０については、この限りでないことを加えておく。
【００３６】
また、図５に示すように磁気抵抗素子１９の電源と半導体集積装置２９の電源を共通電源４０にすることにより、間欠動作時でも、同一のレギュレータから電源を供給することができる。
【００３７】
（実施の形態５）
図６は、本発明の第５の実施の形態を示す磁気信号検出装置の実装配置図である。磁気抵抗素子１９の第１の出力端子１５は、第１のスルーホール３１で多層基板の第１の内層パターン５１に接続し、磁気抵抗素子１９の第２の出力端子１６は、第２のスルーホール３２で多層基板の第２の内層パターン５２に接続している。多層基板の第１の内層パターン５１は、第３のスルーホール３３で第１の演算増幅器２１の非反転入力端子に接続しており、多層基板の第２の内層パターン５２は、第４のスルーホール３４で第２の演算増幅器２２の非反転入力端子に接続している。このように構成することにより、第１の出力端子１５と第２の出力端子１６からの信号に外部からのノイズの影響を受けにくくすることが可能となる。
【００３８】
図７では、更に第１の演算増幅器２１の非反転入力端子と第２の演算増幅器２２の非反転入力端子の間に第５のスルーホール３０を設けており、この端子を接地させることで第１の演算増幅器２１の非反転入力端子と第２の演算増幅器２２の非反転入力端子の間の分離特性を向上させ、互いの干渉を削減するようにしている。
【００３９】
【発明の効果】
以上のように本発明によれば、抵抗ブリッジ回路を構成する第１の磁気抵抗と第２の磁気抵抗の接続点を第１の出力端子とするとともに第３の磁気抵抗と第４の磁気抵抗の接続点を第２の出力端子とし、前記第１の磁気抵抗と前記第４の磁気抵抗の接続点を電源端子とし、前記第２の磁気抵抗と前記第３の磁気抵抗の接続点を接地し、前記第１の出力端子を第１の演算増幅器に接続し、前記第２の出力端子を第２の演算増幅器に接続し、前記第１の演算増幅器の出力端子と前記第２の演算増幅器の出力端子とを前記第３の演算増幅器に接続し、電源端子を間欠動作させるとともに、前記第１および第３の磁気抵抗は、前記第２および第４の磁気抵抗より小さい抵抗値を有し、前記第１の演算増幅器の入力端子を第１のコンデンサを介して接地したものであるので、コモンモードノイズがキャンセルされ、磁気信号検出装置の耐ノイズ特性が向上できるとともに、演算増幅器の入力オフセット電圧の変動による誤動作を防止でき、高周波的に低インピーダンス化され、電源電圧の間欠動作時に安定に動作させることが可能となり、磁気信号検出装置が誤動作するという課題を解決することができるという有利な効果が得られる。
【図面の簡単な説明】
【図１】本発明の実施の形態１による磁気信号検出装置を示す電気回路図
【図２】本発明の実施の形態２による磁気信号検出装置を示す上面配置図
【図３】本発明の実施の形態３による磁気信号検出装置を示す上面配置図
【図４】本発明の実施の形態４による磁気信号検出装置を示す電気回路図
【図５】本発明の実施の形態４による磁気信号検出装置を示す電気回路図
【図６】本発明の実施の形態５による磁気信号検出装置を示す実装配置図
【図７】本発明の実施の形態５による磁気信号検出装置を示す実装配置図
【図８】従来の磁気信号検出装置を示す電気回路図
【符号の説明】
１１第１の磁気抵抗
１２第２の磁気抵抗
１３第３の磁気抵抗
１４第４の磁気抵抗
１５第１の出力端子
１６第２の出力端子
１７電源端子
１８接地端子
１９磁気抵抗素子
２０第３の演算増幅器
２１第１の演算増幅器
２２第２の演算増幅器
２３第１の固定抵抗
２４第２の固定抵抗
２５第３の固定抵抗
２６信号出力端子
２７第１のコンデンサ
２９半導体集積装置
３０第５のスルーホール
３１第１のスルーホール
３２第２のスルーホール
３３第３のスルーホール
３４第４のスルーホール
５１第１の内層パターン
５２第２の内層パターン[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a magnetic signal detection device used for mobile communication devices such as a mobile phone, a cordless phone, and a pager.
[0002]
[Prior art]
Conventionally, this type of magnetic signal detection apparatus has a configuration shown in FIG. In FIG. 8, 11 is a first magnetoresistance, 12 is a second magnetoresistance, 13 is a third magnetoresistance, 14 is a fourth magnetoresistance, 15 is a first output terminal, and 16 is a second output. A terminal 17, a power supply terminal 18, a ground terminal 18, an operational amplifier 20, and a signal output terminal 26, the first magnetoresistor 11, the second magnetoresistor 12, and the third magnetometer that change according to the strength of the magnetic field. Due to the change in the current flowing from the power supply terminal 17 to the resistor 13 and the fourth magnetoresistor 14, the DC voltage of the first output terminal 15 and the second output terminal 16 is directly input to the operational amplifier 20, and the magnetic signal We were detecting.
[0003]
[Problems to be solved by the invention]
However, in the configuration of the above-described prior art, the magnetic signal detection device malfunctions when disturbance noise is input to the operational amplifier, when the input offset voltage of the operational amplifier fluctuates in temperature, or when the power supply voltage is intermittently operated. There was a problem. This magnetic signal detection device is required to have improved noise resistance characteristics, reduced input offset voltage dependency of an operational amplifier, and stable operation during intermittent operation of a power supply voltage.
[0004]
The present invention cancels common mode noise of a magnetic signal detector by grounding the input terminal of a differential operational amplifier circuit composed of a first operational amplifier and a second operational amplifier through a capacitor. An object of the present invention is to improve noise resistance and reduce impedance at high frequencies to prevent malfunction due to fluctuations in the input offset voltage of an operational amplifier and to realize stable operation during intermittent operation of a power supply voltage.
[0005]
[Means for Solving the Problems]
In order to solve this problem, a magnetic signal detection device according to the present invention uses a connection point between a first magnetoresistor and a second magnetoresistor constituting a resistor bridge circuit as a first output terminal and a third magnetoresistor. And the fourth magnetoresistive connection point as a second output terminal, the first magnetic resistance and the fourth magnetic resistance connection point as a power supply terminal, and the second magnetic resistance and the third magnetic resistance. The connection point of the resistor is grounded, the first output terminal is connected to the first operational amplifier, the second output terminal is connected to the second operational amplifier, and the output terminal of the first operational amplifier The output terminal of the second operational amplifier is connected to the third operational amplifier, the power supply terminal is operated intermittently, and the first and third magnetoresistances are more effective than the second and fourth magnetoresistances. Having a small resistance value, the input terminal of the first operational amplifier being Through the first capacitor is characterized in that ground.
[0006]
This cancels the common mode noise of the magnetic signal detector and improves noise resistance, prevents malfunctions due to fluctuations in the input offset voltage of the operational amplifier , and lowers the impedance at high frequencies, making it stable during intermittent operation of the power supply voltage Operation is possible.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
According to the first aspect of the present invention, the connection point between the first magnetoresistor and the second magnetoresistor constituting the resistor bridge circuit is used as the first output terminal, and the third magnetoresistor and the fourth magnetoresistor are connected. The connection point of the magnetoresistor is the second output terminal, the connection point of the first magnetoresistor and the fourth magnetoresistor is the power supply terminal, and the connection point of the second magnetoresistor and the third magnetoresistor is The first output terminal is connected to the first operational amplifier, the second output terminal is connected to the second operational amplifier, the output terminal of the first operational amplifier and the second operational amplifier The output terminal of the operational amplifier is connected to the third operational amplifier, the power supply terminal is operated intermittently, and the first and third magnetoresistors have resistance values smaller than those of the second and fourth magnetoresistors. And having an input terminal of the first operational amplifier through a first capacitor Is obtained by land, common mode noise is canceled, thereby improving the noise immunity of the magnetic signal detection apparatus, and prevent malfunction due to fluctuation of the input offset voltage of the operational amplifier is a high frequency low impedance, supply voltage It is possible to realize stable operation without malfunction during intermittent operation.
[0008]
According to a second aspect of the present invention, the first magnetoresistance and the third magnetoresistance are arranged in the same direction, the second magnetoresistance and the fourth magnetoresistance are arranged in the same direction, and the first magnetoresistance And an arrangement direction of the third magnetoresistance and an arrangement direction of the second magnetoresistance and the fourth magnetoresistance are configured to be perpendicular to each other. This has the effect of maximizing the output voltage between the first output terminal and the second output terminal with respect to a constant magnetic field.
[0009]
According to a third aspect of the present invention, the first magnetic resistance and the third magnetic resistance have the same resistance value, and the second magnetic resistance and the fourth magnetic resistance have the same resistance value. The magnetic signal detection device according to claim 1 is configured and has an effect of preventing chattering of the magnetic signal detection device when there is no magnetic field.
[0010]
In the present invention, a first fixed resistor is connected between the inverting input terminal of the first operational amplifier and the output terminal of the first operational amplifier, and the inverting input terminal of the second operational amplifier and the second operational amplifier are connected to each other. A second fixed resistor is connected between the output terminals, a third fixed resistor is connected between the inverting input terminal of the first operational amplifier and the inverting input terminal of the second operational amplifier, and the first fixed resistor is connected. And the second fixed resistor have the same resistance value, and the third fixed resistor has a smaller resistance value than the first fixed resistor and the second fixed resistor. The positive gain of the differential operational amplifier circuit composed of one operational amplifier and the second operational amplifier has the effect of improving the noise resistance characteristics of the magnetic signal detector.
[0011]
In the present invention, a first fixed resistor is connected between the inverting input terminal of the first operational amplifier and the output terminal of the first operational amplifier, and the inverting input terminal of the second operational amplifier and the second operational amplifier are connected to each other. A second fixed resistor is connected between the output terminals, a third fixed resistor is connected between the inverting input terminal of the first operational amplifier and the inverting input terminal of the second operational amplifier, and the first magnetic resistance A resistance bridge composed of the first, second, third, and fourth magnetoresistors is used as the magnetoresistive element, and the first operational amplifier, the second operational amplifier, the third operational amplifier, By using a circuit block composed of the fixed resistor, the second fixed resistor, and the third fixed resistor as a semiconductor integrated device, the magnetic signal detecting portion can be mounted independently at an arbitrary location.
[0012]
The present invention has an effect of preventing disturbance noise from being superimposed on the output voltage by connecting the magnetoresistive element and the semiconductor integrated device by the inner layer wiring of the multilayer substrate.
[0013]
The present invention provides a semiconductor integrated device including the first operational amplifier, the second operational amplifier, the third operational amplifier, the first fixed resistor, the second fixed resistor, and the third fixed resistor. By providing a ground terminal between the inverting input terminal of the first operational amplifier and the inverting input terminal of the second operational amplifier, the non-inverting input terminal of the first operational amplifier and the non-inverting terminal of the second operational amplifier are provided. It has the effect of improving the separation characteristics of the input terminals and preventing malfunction of the magnetic signal detection device.
[0014]
According to the present invention, the power supply terminal of the magnetoresistive element and the power supply of the semiconductor integrated device are configured to be supplied from a common power supply path, so that the power can be supplied from the same regulator even during intermittent operation.
[0015]
Hereinafter, embodiments of the present invention will be described with reference to FIGS.
[0016]
(Embodiment 1)
FIG. 1 is an electric circuit diagram showing a magnetic signal detection device according to a first embodiment of the present invention. The first magnetoresistor 11, the second magnetoresistor 12, the third magnetoresistor 13, and the fourth magnetoresistor 14 serve as a magnetoresistive element 19 having a resistance bridge circuit configuration. The connection point of the magnetic resistance 14 is a power supply terminal 17, and the connection point of the second magnetic resistance 12 and the third magnetic resistance 13 is a ground terminal 18. The connection point between the first magnetoresistor 11 and the second magnetoresistor 12 is used as the first output terminal 15, and the third magnetoresistor 13 and the fourth magnetoresistor 14 are used as the second output terminal 16.
[0017]
Due to the DC voltage applied from the power supply terminal 17, a current flows through the magnetoresistive element 19, a DC voltage corresponding to the voltage drop of the current flowing through the first magnetoresistor 11 is generated at the first output terminal 15, and the second A DC voltage corresponding to the voltage drop of the current flowing through the fourth magnetic resistor 14 is generated at the output terminal 16. The power supply terminal 17 and the ground terminal 18 and the first output terminal 15 and the second output terminal 16 of the magnetoresistive element 19 may be arranged so as to face each other.
[0018]
In this state, the first output terminal 15 is connected to the non-inverting input terminal of the first operational amplifier 21, and the second output terminal 16 is connected to the non-inverting input terminal of the second operational amplifier 22. Has been. In this way, the DC voltage signal from the first output terminal 15 is compared by the first operational amplifier 21, and the DC voltage signal from the second output terminal 16 is compared by the second operational amplifier 22. The circuit can be operated in a dynamic manner, and even if the internal offset voltages of the first operational amplifier 21 and the second operational amplifier 22 change due to fluctuations in the ambient temperature environment, the direct current from the first output terminal 15 The voltage signal and the DC voltage signal from the second output terminal 16 are prevented from relatively changing.
[0019]
Further, even if common mode noise is input to the non-inverting input terminal of the first operational amplifier 21 and the non-inverting input terminal of the second operational amplifier 22 through the first output terminal 15, the output of the first operational amplifier 21 is output. The common mode noise is canceled between the terminal and the output terminal of the second operational amplifier 22, and as a result, the noise resistance is improved.
[0020]
The first fixed resistor 23 is connected between the non-inverting input terminal of the first operational amplifier 21 and the output terminal of the first operational amplifier 21, and the first operational amplifier 21 is subjected to non-inverting DC amplification. Yes. The second fixed resistor 24 is connected between the non-inverting input terminal of the second operational amplifier 22 and the output terminal of the second operational amplifier 22, and the second operational amplifier 22 is non-inverting DC amplified. I am letting. The third fixed resistor 25 is connected between the inverting input terminal of the first operational amplifier 21 and the inverting input terminal of the second operational amplifier 22, and is connected to the inverting input terminal of the first operational amplifier 21. It is provided in order to make the DC potential between the inverting input terminals of the second operational amplifier 22 common. The third operational amplifier 20 is provided to compare the DC voltage output of the first operational amplifier 21 and the DC voltage output of the second operational amplifier 22, and the first magnetoresistor 11 and the second magnetoresistor 12. And the third magnetic resistance 13 and the fourth magnetic resistance 14 are operated as a comparator for finally discriminating the magnetic signals detected.
[0021]
Here, the first capacitor 27 is connected between the non-inverting input terminal of the first operational amplifier 21 and the ground. As described above, the input impedance of the non-inverting input terminal of the first operational amplifier 21 is lowered at a high frequency with respect to the frequency determined by the first capacitor 27, thereby preventing malfunction of magnetic signal detection. Even if the power supply terminal 17 is intermittently operated (pulse-like operation), it can be stably operated.
[0022]
The first capacitor 27 is preferably connected between the vicinity of the non-inverting input terminal of the first operational amplifier 21 and the ground, and in some cases, between the vicinity of the non-inverting input terminal of the second operational amplifier 22 and the ground. You may connect to. Further, the first capacitor 27 may be connected between both the vicinity of the non-inverting input terminal of the first operational amplifier 21 and the ground and between the vicinity of the non-inverting input terminal of the second operational amplifier 22 and the ground. Keep it. Further, it is added that there is no problem even if the power supplies of the first operational amplifier 21, the second operational amplifier 22, and the third operational amplifier 20 are intermittently operated at the same timing as the power supply terminal 17.
[0023]
Next, a specific operation will be described. A magnet is provided on the car adapter side that holds the mobile phone, and a magnetoresistive element 19 is provided on the mobile phone side. When the mobile phone is attached to or brought close to the car adapter, the magnetoresistive element 19 on the mobile phone side reacts with the magnet provided on the car adapter side, and the DC potential of the first output terminal 15 and the second output terminal 16 Is reversed. This signal is DC-amplified by the first operational amplifier 21 and the second operational amplifier 22 and finally discriminated by the third operational amplifier 20. The hooking operation of the mobile phone is automatically operated based on the determined signal. That is, when the mobile phone is attached to or brought close to the car adapter, it is controlled to be off-hook. On the other hand, if the mobile phone is controlled to be on-hook when it is attached to or detached from the car adapter, it can be automatically hooked.
[0024]
(Embodiment 2)
FIG. 2 is a top plan view of a magnetic signal detection device showing a second embodiment of the present invention. As shown in FIG. 2, the first magnetoresistor 11 and the third magnetoresistor 13 are arranged in the horizontal direction, and the second magnetoresistor 12 and the fourth magnetoresistor 14 are arranged in the vertical direction. In this state, the first magnetoresistor 11, the second magnetoresistor 12, the third magnetoresistor 13 and the fourth magnetoresistor 14 are inclined by 90 degrees with respect to the adjacent magnetoresistors. It is arranged.
[0025]
By arranging in this way, only the second magnetoresistor 12 and the fourth magnetoresistor 14 in the diagonal positions react to the magnetic field in the direction of the power supply terminal 17 and the ground terminal 18, As a result, the resistance values of the second magnetoresistor 12 and the fourth magnetoresistor 14 change, and the DC potentials of the first output terminal 15 and the second output terminal 16 change to detect a magnetic signal. It becomes possible.
[0026]
At this time, the first magnetoresistor 11, the second magnetoresistor 12, the third magnetoresistor 13 and the fourth magnetoresistor 14 are made of the same component, and the temperature of the resistor material The temperature characteristics of the magnetic signal detector are improved by aligning the coefficients.
[0027]
Note that the four magnetoresistances of the first magnetoresistance 11, the second magnetoresistance 12, the third magnetoresistance 13, and the fourth magnetoresistance 14 do not necessarily have to be made of the same material. Add.
[0028]
In addition, the first magnetoresistor 11 and the third magnetoresistor 13 have the same resistance value, the second magnetoresistor 12 and the fourth magnetoresistor 14 have the same resistance value, and the first magnetoresistor 11 and the first magnetoresistor 11 have the same resistance value. 3 (ie, the first and third magnetic resistances 11 and 13 are smaller than the resistance values of the second and fourth magnetic resistances 12 and 14). ing.). By configuring in such a relationship, chattering prevention of the magnetic signal detection device in a state where there is no magnetic signal is realized, and the magnetic signal detection device can be stably operated.
[0029]
The first magnetoresistor 11 and the third magnetoresistor 13 may have larger resistance values than the second magnetoresistor 12 and the fourth magnetoresistor 14.
[0030]
The first fixed resistor 23 and the second fixed resistor 24 have the same resistance value, and the third fixed resistor 25 has a smaller resistance value than the first fixed resistor 23 and the second fixed resistor 24. At this time, the resistance value of the third fixed resistor 25 is set so as to be at least greater than 1/5 of the resistance value of the first fixed resistor 23 and the second fixed resistor 24. Therefore, consideration is given so that the outputs of the first operational amplifier 21 and the second operational amplifier 22 do not decrease.
[0031]
(Embodiment 3)
FIG. 3 is a top plan view of a magnetic signal detection device showing a third embodiment of the present invention. In addition, about the part of the same structure as 2nd Embodiment, the same number is attached | subjected and detailed description is abbreviate | omitted. As shown in the drawing, a resistance bridge circuit composed of a first magnetoresistor 11, a second magnetoresistor 12, a third magnetoresistor 13, and a fourth magnetoresistor 14 is configured as a magnetoresistive element 19. Thus, by comprising, only the part which detects a magnetic resistance can be made independent, and it becomes possible to arrange this magnetoresistive element 19 in arbitrary places.
[0032]
Further, the power supply terminal 17 that is a connection point between the first magnetic resistance 11 and the fourth magnetic resistance 14 and the ground terminal 18 that is a connection point between the second magnetic resistance 12 and the third magnetic resistance 13 and the first magnetic resistance. The first output terminal 15 that is the connection point of the resistor 11 and the second magnetic resistor 12 and the second output terminal 16 that is the connection point of the third and fourth magnetic resistors 13 and 14 are both magnetic. Terminals are provided at the four corners of the resistance element 19 so that the distance between the terminals is maximized. With this arrangement, the separation characteristics between the terminals can be improved, and interference between adjacent terminals can be reduced.
[0033]
(Embodiment 4)
FIG. 4 is an electric circuit diagram of a magnetic signal detecting apparatus showing a fourth embodiment of the present invention. In addition, about the part of the structure same as 1st Embodiment, the same number is attached | subjected and detailed description is abbreviate | omitted. As shown in FIG. 4, the magnetoresistive element 19 is composed of a resistance bridge circuit composed of a first magnetoresistor 11, a second magnetoresistor 12, a third magnetoresistor 13, and a fourth magnetoresistor 14, and a semiconductor. The integrated device 29 includes a first operational amplifier 21, a second operational amplifier 22, a third operational amplifier 20, a first fixed resistor 23, a second fixed resistor 24, and a third fixed resistor 25. Yes.
[0034]
As described above, by dividing the magnetic signal detection part and the output signal processing part, the magnetic signal detection unit can be configured at an arbitrary position, and the degree of freedom for mounting the components is improved. The overall mounting efficiency can be improved.
[0035]
The first operational amplifier 21 and the second operational amplifier 22 are preferably semiconductor integrated devices manufactured by the same process, but the third operational amplifier 20 is not limited to this.
[0036]
Further, as shown in FIG. 5, by using the common power source 40 for the magnetoresistive element 19 and the semiconductor integrated device 29, it is possible to supply power from the same regulator even during intermittent operation.
[0037]
(Embodiment 5)
FIG. 6 is a mounting layout diagram of the magnetic signal detection device showing the fifth embodiment of the present invention. The first output terminal 15 of the magnetoresistive element 19 is connected to the first inner layer pattern 51 of the multilayer substrate through the first through hole 31, and the second output terminal 16 of the magnetoresistive element 19 is connected to the second through-hole 31. The holes 32 are connected to the second inner layer pattern 52 of the multilayer substrate. The first inner layer pattern 51 of the multilayer substrate is connected to the non-inverting input terminal of the first operational amplifier 21 through the third through hole 33, and the second inner layer pattern 52 of the multilayer substrate is connected to the fourth through hole. The hole 34 is connected to the non-inverting input terminal of the second operational amplifier 22. With this configuration, it is possible to make the signals from the first output terminal 15 and the second output terminal 16 less susceptible to external noise.
[0038]
In FIG. 7, a fifth through-hole 30 is further provided between the non-inverting input terminal of the first operational amplifier 21 and the non-inverting input terminal of the second operational amplifier 22, and the terminal is grounded by grounding this terminal. The isolation characteristic between the non-inverting input terminal of the first operational amplifier 21 and the non-inverting input terminal of the second operational amplifier 22 is improved, and mutual interference is reduced.
[0039]
【The invention's effect】
As described above, according to the present invention, the connection point between the first magnetoresistance and the second magnetoresistance constituting the resistance bridge circuit is used as the first output terminal, and the third magnetoresistance and the fourth magnetoresistance are used. Is the second output terminal, the connection point of the first magnetoresistor and the fourth magnetoresistor is the power supply terminal, and the connection point of the second magnetoresistor and the third magnetoresistor is grounded. The first output terminal is connected to a first operational amplifier, the second output terminal is connected to a second operational amplifier, and the output terminal of the first operational amplifier and the second operational amplifier Are connected to the third operational amplifier, the power supply terminal is intermittently operated, and the first and third magnetoresistances have smaller resistance values than the second and fourth magnetoresistances. The input terminal of the first operational amplifier is grounded through the first capacitor. Since those were, common mode noise is canceled, it is possible to improve noise characteristics of the magnetic signal detection apparatus, can prevent malfunction due to fluctuation of the input offset voltage of the operational amplifier is a high frequency low impedance, supply voltage It is possible to stably operate during the intermittent operation, and an advantageous effect that the problem that the magnetic signal detection device malfunctions can be solved.
[Brief description of the drawings]
FIG. 1 is an electric circuit diagram showing a magnetic signal detection device according to a first embodiment of the present invention. FIG. 2 is a top plan view showing a magnetic signal detection device according to a second embodiment of the present invention. FIG. 4 is an electrical circuit diagram showing a magnetic signal detection device according to a fourth embodiment of the present invention. FIG. 5 is a magnetic signal detection device according to a fourth embodiment of the present invention. FIG. 6 is a mounting layout diagram showing a magnetic signal detection device according to a fifth embodiment of the present invention. FIG. 7 is a mounting layout diagram showing a magnetic signal detection device according to a fifth embodiment of the present invention. ] Electrical circuit diagram showing a conventional magnetic signal detector [Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 1st magnetoresistance 12 2nd magnetoresistance 13 3rd magnetoresistance 14 4th magnetoresistance 15 1st output terminal 16 2nd output terminal 17 Power supply terminal 18 Ground terminal 19 Magnetoresistance element 20 3rd Operational amplifier 21 First operational amplifier 22 Second operational amplifier 23 First fixed resistor 24 Second fixed resistor 25 Third fixed resistor 26 Signal output terminal 27 First capacitor 29 Semiconductor integrated device 30 Fifth through Hole 31 First through hole 32 Second through hole 33 Third through hole 34 Fourth through hole 51 First inner layer pattern 52 Second inner layer pattern

Claims

The connection point between the first magnetoresistor and the second magnetoresistor constituting the resistor bridge circuit is used as the first output terminal, and the connection point between the third magnetoresistor and the fourth magnetoresistor is used as the second output terminal. The connection point between the first magnetoresistance and the fourth magnetoresistance is a power supply terminal, the connection point between the second magnetoresistance and the third magnetoresistance is grounded, and the first output terminal is the first output terminal. The second operational amplifier is connected to the second operational amplifier, and the output terminal of the first operational amplifier and the output terminal of the second operational amplifier are connected to the third operational amplifier. Connected to the amplifier,
While intermittently operating the power terminal,
The first and third magnetoresistances have a smaller resistance value than the second and fourth magnetoresistances,
A magnetic signal detection apparatus characterized in that an input terminal of the first operational amplifier is grounded via a first capacitor.

The first magnetoresistance and the third magnetoresistance are arranged in the same direction, the second magnetoresistance and the fourth magnetoresistance are arranged in the same direction, and the first magnetoresistance and the third magnetoresistance are arranged in the same direction. The magnetic signal detection device according to claim 1, wherein an arrangement direction, the second magnetic resistance, and the fourth magnetic resistance are arranged at right angles.

2. The magnetism according to claim 1, wherein the first magnetoresistance and the third magnetoresistance have the same resistance value, and the second magnetoresistance and the fourth magnetoresistance have the same resistance value. Signal detection device.